Thursday, December 10, 2015

How This Year’s El Niño Will Make Meteorologists Look Dumb

Despite the bump higher on yesterday's report of the first withdrawal
from storage this season the market is very oversupplied. Even more
important for strategists, despite the hype of "the Godzilla El Niño" it
is not easy to nail down the effects for this season. The U.S. won't
necessarily see the lowest number of heating degree days in the history
of the world....

What it comes down to is: every El Niño is different.
From Popular Science:

California mudslides! Florida tornadoes! Killer New England ice storms!
Is that the kind of weather we’re in for this year?

No, all that happened back in the winter of 1997-98—courtesy of one ornery El Niño.
While the once-every-several years weather pattern has already caused
100-year flooding on India's eastern coast, it probably won't do much
harm in the U.S.

Yet, some forecasts for this season sound ominously similar to 1997,
drawing catastrophizing prognostications from some quarters—as well as
hopes for a California-drought-ending deluge in others. Both sides may
be disappointed.

The Facts
Let’s review what we know: The ocean’s surface temperatures are
warmer than usual, and that’s what drives El Niño weather. The global
pattern sets up every three to seven years or so, and it usually brings
mild winters in some places—Japan, the U.S. Northeast—and very wet ones
in others, such as the American southeast and in parts of the tropics.

A report last week called attention to rising the ocean surface
temperatures, which have reached a peak that beats the 1997-98 El Niño.
That’s a bad sign. But the prediction models actually call for a more
moderate, traditional El Niño pattern: wet across the south, warm across
the north.

“Even if the ocean temperatures are exactly the same [as in a
powerful El Niño year] that doesn’t mean the impacts will be,” says Mike
Halpert, the deputy director of the National Weather Service’s Climate
Prediction Center.

Here’s Why
The surface of the equatorial ocean is indeed super warm. That’s the
first ingredient for a record year. But the second part of the equation
is atmosphere: For record conditions, the air in the tropics needs to
take up lots of extra moisture.

That then produces higher rainfall across the equator, which
butterfly-effects its way into the unusually warm and wet conditions in
the U.S.
So far, the second part of the equation isn’t happening the same
way—the atmosphere in the tropics is drier than it was during the
1997-98 season.

Weather is, of course, a squirrely thing. But as it stands this El Niño is looking milder than that record-breaking year.

Take a look at these maps for re-assurance. We’ve overlaid the prediction for this winter with the records of the last Big One.